1. Field of the Invention
The present invention relates to in-vehicle audio devices, to be mounted to motor vehicles, capable of generating sound image at a localized position to which a visual line of a driver of a host vehicle is guided.
2. Description of the Related Art
There have been known techniques for generating a sound image, by using a plurality of speakers mounted to a motor vehicle, to be localized or positioned in a direction of a visual line of a driver of the motor vehicle, toward which an attention attraction object (as a target object) to pay attention to is present. This conducts the driver of the motor vehicle to pay his attention toward the target object. However, in general, conventional techniques consider a horizontal direction only, not a vertical direction when generating a sound image at a localized position in a direction of the visual line of the driver. Accordingly, there is a possibility of it being difficult to correctly and quickly guide the visual line of the driver to the localized position of the generated sound image because the localized position of the generated sound image becomes too high or low due to a mounted position of each of the speakers arranged in a passenger compartment of the motor vehicle and a height of the motor vehicle.
In order to solve such a problem of the conventional technique, there is another conventional technique, for example, Japanese patent laid open publication No. 2009-166700, which discloses a technique in which plural speakers are arranged in a vertical direction of a passenger compartment of a motor vehicle in order to adjust a localized position of a sound image along a vertical direction of the motor vehicle.
However, the conventional technique is required to arrange plural speakers at different positions along a vertical direction of the passenger compartment of the motor vehicle. It is therefore difficult to apply such a technique to many currently available motor vehicles which are equipped with speakers of a usual type, and is required to arrange one or more additional speakers in the passenger compartment of the motor vehicle.